1. Field of the Invention
The present invention relates to a device for scrubbing substrates such as semiconductor wafers, LCD substrates, photo-masks, ceramic substrates, compact disks and printed substrates by a brush while applying solution to substrates.
2. Description of the Related Art
In the case of the substrate scrubbing devices, contaminating particles can be removed from the wafer surface in such a way that the brush having nylon or mohair fibers planted is pushed against the semiconductor wafer while rotating the wafer together with spin chuck and applying cleaning solution to the wafer.
Japanese Patent Disclosure Sho 57-45233 discloses a device wherein vortexes are caused in a vortex chamber of the spin chuck and negative pressure caused by these vortexes is used to hold the semiconductor wafer. The vortex chamber has openings in the surface of the chuck and an inlet formed in a side wall thereof communicated with a passage in a rotating shaft of the spin chuck. In short, pressurized gas or solution is jetted into the vortex chamber through the inlet to cause vortexes in the vortex chamber.
In the case of this type of conventional device, however, dust such as particles caused in bearings are blown together with solution to the semiconductor wafer. They are thus caused to adhere to the bottom surface of the wafer, thereby causing the productivity to be lowered. In addition, they are also caused to enter into a motor to break it down.
Japanese Patent Publication Hei 3-9607 discloses a spin chuck of the grip type wherein the wafer is gripped at its outer rim by three or more claws. In the case of this type of spin chuck, however, the device becomes complicated in structure and large in size because it must have drive sources for two system lines.
Furthermore, a spin chuck wherein weights are connected to chuck sections which can move toward the rotating center of the wafer and the chuck sections are moved by centrifugal force added to the weights when the wafer is rotated. The wafer is held by the chuck sections thus moved. In the case of this type of spin chuck, however, the extent to which the chuck sections can be moved becomes smaller when the rotation of the wafer is started and stopped. This makes it impossible to stably hold the wafer.